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Species and Strain Differences in the Toxicity of the Alga Gambierdiscus: Implications for Ciguatera Fish Poisoning in the Caribbean

Project Status: This project began in January 2011 and is projected to be completed in December 2015

The goal of this project is to advance our understanding of toxins produced by different species of the alga Gambierdiscus and how these toxins and their varieties move through the food chain. Project results will increase our understanding of the factors contributing to ciguatera food poisoning and how it may differ between the Atlantic and Pacific oceans. Simultaneously, we will develop a fast and inexpensive toxin test.

Why We Care
Ciguatera fish poisoning (CFP) causes more human illness than all other harmful algal bloom species combined. Unfortunately, little is known about the different chemical forms (congeners) of marine toxins (ciguatoxins) produced by different species of the alga Gambierdiscus. This study will lead to a better understanding of the differences in toxicity among species of Gambierdiscus, allowing managers to design effective monitoring programs in the short term and develop risk assessments and forecasting capabilities in the long term.

What We Are Doing
We are conducting a comprehensive survey of the differences in toxicity within and among various species of Gambierdiscus in the Caribbean. We will establish the relative per cell toxicity of Gambierdiscus species and varieties (isolates) and provide detailed analyses of the ciguatoxin congeners produced by the most toxic species. This will allow testing of the hypothesis that per cell toxicity increases with latitudinal gradients in the Caribbean, and will also enable comparison of toxin profiles from Atlantic and Pacific strains. We will also assess whether or not a test for the breakdown of red blood cells (hemolytic assays) can be used as a low-cost method for determining relative CFP toxicity among isolates, which will further our understanding of regional differences in toxicity among Gambierdiscus species.

The project team included partners from NOAA/NCCOS and North Carolina State University at Raleigh.

Benefits of Our Work
This project will provide valuable information about ciguatoxins entering the food chain. For the first time, we will systematically address whether the amounts and types of ciguatoxins being produced in the Caribbean are different from those in the Pacific, and whether isolates from lower latitudes are more toxic. This knowledge is crucial for understanding CFP and how it may differ between the Atlantic and Pacific basins. It will also help determine the success of a cell-based monitoring system for predicting CFP risk. Development of a fast and low-cost assay to determine relative CFP toxicity among isolates can help manage CFP risk. Similarly, experiments designed to investigate how growth conditions affect relative toxicity might inform future Gambierdiscus management strategies.